The operating parameters for operating a proximity switch can differ depending on the type of switch and also because of manufacturing tolerances. Up until now, for example, many parameters have determined the echo-time evaluation of an ultrasonic proximity switch in a mask-programmed microprocessor. To enable manufacturing tolerances to be compensated for in electronic components and ultrasonic transducers, it is advantageous to retain the operating parameters as variable operating parameters until the ultrasonic proximity switch is used. Moreover, such a flexible operation makes it possible for one to react to new developments in ultrasonic transducers and to customer-specific solutions for an ultrasonic proximity switch.
Up until now, to solve this problem, the operating parameters were stored in the program memory of a mask-programmed microprocessor. For this purpose, solutions entailing pull-up resistors on the microprocessor were applied. In this case, however, the disadvantage arose that one was only able to react to new developments in the ultrasonic transducer and to customer-specific design approach solutions with a relatively high expenditure of time and energy for circuit engineering.
To adjust operating parameters in ultrasonic sensors, it is furthermore known (see the prospectus Ultrasonic Sensors, International Edition '91 by Pepperl & Fuchs) to use encoding switches in the clamping space, whereby the encoding switch is used to switch over from the switching output to the serial interface. This means that from a standpoint of circuit engineering, time and energy must be expended for the short-circuit-proof switching output and for the required voltage level for the serial interface. However, this solution requires additional expenditure for circuit wiring. Furthermore, it is disadvantageous that space is needed, which leads to problems, for example, in applications using compact proximity switches.